JPH02290940A - Bearing alloy - Google Patents

Abstract

PURPOSE:To improve the fatigue resistance and seizure resistance of the bearing alloy by extruding a billet formed by adding Pb-Sb alloy powder under prescribed conditions to Al alloy powder contg. lubricating components and hard components. CONSTITUTION:A billet constituted of mixed powder of an Al alloy and a Pb-Sb alloy is extruded to form the bearing alloy. The billet is formed by adding, by weight, 5 to 20% Pb-Sb alloy powder contg. 25 to 30% Sb to Al alloy powder. The above Al alloy includes lubricating components, hard components, reinforcing components and grain refining components; above all, the lubricating components and the hard components are included as essential components.

Description

[Detailed description of the invention] [Purpose of the invention]

(Field of Industrial Application) The present invention relates to a bearing base metal that is suitably used as a material for bearings and a material for sliding members used as components of various mechanical devices such as automobiles and machine tools. This relates to an aluminum-based bearing alloy that is lighter than other bearing materials and has superior seizure resistance and fatigue resistance. (Prior art) Conventionally, alloys used as materials for sliding bearings contain C.
U-Pb series, Babbitt series, etc. are used depending on the purpose of use, etc., but in recent years, especially as bearing base metals for internal combustion engines, they have been used in terms of heat resistance, wear resistance, corrosion resistance, fatigue resistance, etc. However, it had the disadvantage that it could not fully satisfy the strict requirements of the parts in which it was used. In contrast, the present inventors have
As disclosed in Publication No. 7, seizure resistance is improved by extruding a billet formed by mixing AM-Pb-St based atomized alloy powder and individual Pb powder at an extrusion ratio of 10 or more. We have developed a bearing base metal that has excellent seizure resistance due to the addition of a large amount of Pb, which significantly improves the corrosion resistance, and has high alloy strength and excellent fatigue resistance. In this alloy structure, the Pb originally contained in the aluminum alloy powder is uniformly and finely dispersed in the matrix, and the Pb grains added alone are dispersed in the structure as coarse particles. As a result of further various experimental studies, the present inventors found that the reason why the scorching property of the above-mentioned alloy system is significantly improved is due to the main effect of the coarse grains of Pb added alone. The conclusion was that this was due to the This is due to the fine P on the sliding surface supplied from aluminum alloy powder.
b tends to disappear when approaching the seizure limit, but this is thought to be because the surface of coarse Pb particles added alone disappears and it is possible to supply new Pb from inside the sliding surface. (Problem to be solved by the invention) However, in this alloy system, if the amount of Pb powder added/mixed as a single powder increases, the liquid phase of Pb will seep between the powder particles during heating for extrusion, resulting in extrusion. This is undesirable because it lowers the properties and the Pb particles become coarse due to the Pb powders bonding together, so the amount of Pb powder added as a single powder was limited to 12% by weight or less. Furthermore, when extruded powder material is used as the raw material for a sliding bearing, it is desirable that the thickness of the extruded material be 2 mm or less, considering the number of subsequent rolling steps and the amount of deformation. However, when producing an extruded material with a thickness of 2 mm or less from this alloy system, defects such as cracks in the extruded material and melting of Pb may occur even if the amount of Pb powder added as a single powder is 12% by weight or less. Pb has the problem of reducing extrudability. (Object of the Invention) The present invention has been made in view of the above-mentioned conventional problems, and by making the Pb grains dispersed by adding them alone to aluminum alloy powder into a Pb-Sb alloy, extrudability is significantly improved. The purpose of this project is to provide an aluminum bearing base metal with excellent fatigue resistance and seizure resistance.

[Structure of the invention]

(Means for Solving the Problems) The aluminum-based bearing base metal having excellent fatigue resistance and seizure resistance according to the present invention has a lubricating component, a hard component, a reinforcing component, and a grain refining component in An. Aluminum alloy powder containing at least a lubricating component and a hard component, Sb: 25~
5-20% by weight of Pb-Sb alloy powder containing 50% by weight
The structure of the aluminum bearing base metal, which has excellent fatigue resistance and seizure resistance, is described above. This is a means to solve the conventional problems. The aluminum-based bearing base metal according to the present invention uses aluminum alloy powder containing at least a lubricating component and a hard component among a lubricating component, a hard component, a reinforcing component, and a grain refining component in AJI. The alloy powder contains An as a main component and Pb as a lubricating component: 3 to 1.
5% by weight, Sn: one or two selected from 5% by weight or less, Sill to 12% by weight as a hard component, Cu, Cr, Mg, Mn, N as a reinforcing component if necessary
i, Zn, Fel) = 0.2 to 5% by weight, Ti, B, Zr, V, Ga, REM as grain refining components if necessary
c7) One or more elements selected from among: 0
．． It is also desirable to use one containing 01-3% by weight. The aluminum-based bearing base metal with excellent fatigue resistance and seizure resistance according to the present invention is produced by using the above-mentioned aluminum alloy powder. Sb: Pb-Sb containing 25-50% by weight
It is formed by extruding a billet formed from a powder to which 5 to 20% by weight of alloy powder is added and mixed, preferably at an extrusion ratio of 40 or more. Next, the aluminum alloy powder and Pb-Sb alloy powder used in the aluminum-based bearing base metal according to the present invention will be explained in more detail. (1) Aluminum alloy powder ■ Lubricating component Pb and Sn are effective as lubricating components;
By adding one or two selected from among these, it is effective for low friction and wear resistance. It is also effective in improving seizure resistance, although this is not a major effect compared to Pb alloys in which Pb is added alone. Pb is superior to Sn in terms of improving the scorching properties. However, if the amount of Pb is less than 3% by weight, seizure resistance and different physical properties tend to be inferior, and if it exceeds 15% by weight, the fatigue strength of the matrix tends to be insufficient, resulting in poor load resistance. Bearing performance becomes difficult to satisfy.
Moreover, if it exceeds 12% by weight, the Pb phase in the atomized alloy powder obtained from a practical molten metal temperature range tends to become coarse and segregated, so it is more preferably 12% by weight or less. In addition, Sn is also effective as a lubricating component like Pb,
It also has the effect of improving the corrosion resistance of Pb. However, if Sn exceeds 5% by weight, the fatigue strength of the matrix will be insufficient, and it will melt into a liquid phase during extrusion, making extrusion defects more likely to occur. ■Hard component It is effective to add St as a hard component. This Si is dispersed in the An matrix as eutectic Si or primary Si, and as a hard substance it contributes to improving bearing strength and wear resistance, but if the amount of St is less than 1% by weight, the effect of adding it is small. If it exceeds 12% by weight, it becomes brittle and tends to impede workability, so 1 to 12% by weight.
It is best to set it within the range of . In addition, St dispersed in the An matrix after extrusion molding
Regarding the particle size, if it exceeds 121 Lm, it will easily damage the mating material, the areal density of the dispersion will decrease, and the wear resistance will deteriorate, so it is recommended that the particle size be 12 JLtq or less. In addition, as in the second manufacturing method of an aluminum bearing base metal disclosed in Japanese Patent Application Laid-Open No. 62-130253, Si
An-8 to 30 wt% Si with a particle size of 6 to 12 pm
There is no problem in adding St in the form of atomized alloy powder. ■Reinforcing components Reinforcing components include Cu, Cr, Mg
, M n , Ni, Zn, Fe, etc. are effective, and adding one or more selected from these elements as necessary is effective in increasing the strength of the An matrix. Among these, Cu is an effective element for increasing creep strength, that is, high temperature softening resistance, and contributes to improving fatigue resistance under high temperature sliding conditions. However, if it is less than 0.2% by weight, the above-mentioned effects will be small, and if it exceeds 5% by weight, a large amount of acicular Cu Al 2 compounds will precipitate, resulting in brittleness and a tendency to reduce fatigue resistance. In addition to Cu, other elements that increase the strength of the An matrix include Cr, Mg, Mn, Ni, Zn, and F.
These are often used as additive elements for aluminum alloy wrought materials, and one or more selected from these elements including Cu are added to 0.2
It may be added in a range of 5% by weight. ■Grain-refining components Crystal grain-refining components include Ti, B, Zr, V, and Ga.
, REM (one or more selected from rare earth elements including Y and Sc) are effective, and these one
It is effective for refining the crystal grains of aluminum alloy by adding one or more seeds as necessary, and it is a lubricating component (Pb, Sn) in aluminum alloy powder.
If necessary, one or more selected from these may be added to a total of 0.00% to promote uniform miniaturization.
It may also be added in a range of 1 to 3% by weight. (2) Pb-Sb alloy powder The Pb-Sb alloy added as a mixed powder to the aluminum alloy powder is mainly used for seizure resistance, conformability,
Effective in improving different physical properties. The Pb-based alloy phase contained in the aluminum alloy is rapidly solidified and has a particle size of 2 to 3 gm or less, since the aluminum alloy powder is usually produced by the atomization method. On the other hand, in order for the Pb-Sb alloy powder to be added or mixed to exhibit the above effects, it is desirable that the particles have an average particle size in the range of 5 to 50 pm. In other words, if it is smaller than 5 gm, when foreign substances such as wear particles get mixed into the sliding surface, the embedding property thereof becomes poor, and galling tends to occur easily. Furthermore, when the seizure limit is approached and Pb begins to disappear from the surface, the lead reservoir effect of supplying Pb from inside to prevent seizure is lost, and seizure is more likely to occur. On the other hand, when the average particle size is larger than 50 pm, the strength of the bearing base metal decreases, and fatigue peeling and cracks are more likely to occur. As already mentioned, the conventional Pb powder added alone is
Although it exhibits various effects, it has the problem of reducing extrudability. Therefore, the Pb-Sb alloy powder added in the present invention is intended to improve extrudability without losing the effect of the Pb powder added alone. In other words, single Pb powder with a melting point of 327°C becomes a liquid phase during heating during extrusion, which tends to cause extrusion defects, but in the present invention, Pb and Sb are added in a range of 25 to 50% by weight. By using the Pb-Sb alloy powder added in step 1, it is possible to suppress the generation of liquid phase during extrusion. Furthermore, by using Pb-Sb alloy powder, the dispersion state of the added powder becomes more uniform than before, which also adds to the effect of improving fatigue strength. However, if Sb in the Pb-Sb alloy is less than 25% by weight, it will enter the liquid phase region at a temperature similar to or lower than the melting point of Pb powder alone, and if it exceeds 50% by weight, it will have less anti-seizure effect than Pb powder alone. This is not preferable because it reduces the amount. The amount of this Pb-Sb alloy powder added to the aluminum alloy powder is preferably 5 to 20% by weight. In other words, if it is less than 5% by weight, it will not have much of an effect on improving seizure resistance, and if it exceeds 20% by weight, even if this alloy powder is added, the liquid phase generated due to local temperature rise due to friction etc. will form between the powder particles. This is undesirable because it oozes out and causes extrusion defects, and it is also undesirable because the Pb-Sb alloy powder particles are combined and become extremely coarse. Next, an example of a method for manufacturing an aluminum bearing base metal having excellent fatigue resistance and seizure resistance according to the present invention will be explained. First, the aluminum alloy powder and Pb-Sb alloy powder are thoroughly mixed using a mixer such as a V-type blender,
After making it uniform, it is formed into a billet using an isostatic press, hydraulic press, etc. Next, this billet is 350~4
Preheat to about 50°C and extrude, preferably at an extrusion ratio of 40 or higher. In this case, if the extrusion ratio deviates from this range, internal cracks and surface cracks of the bearing material after extrusion will occur. Problems such as waviness and breakage may occur. If the bearing material does not have a backing metal, it is then machined to the specified dimensions. On the other hand, when used as a bearing material with lj metal, 1 to 1
While repeating extrusion, rolling, and annealing as a plate material with a thickness of 0 mm, it is clad with a mild steel plate with a C content of about 0.1% by weight, and processed into push-half metal parts. (Function of the Invention) Since the aluminum-based bearing base metal according to the present invention has the above-described structure, by using a Pb-Sb alloy powder in which Sb is added to Pb in a range of 25 to 50% by weight. , the generation of liquid phase during extrusion is suppressed,
Extrudability is improved without losing the effect of conventional Pb added alone, and the effects of preventing defects such as cracking of the extruded material and melting of Pb are brought about. (Example) No. 1 in Table 1. Aluminum alloy powders having the chemical compositions shown in columns 1 to 12 were obtained by an air atomization method in which molten aluminum alloy at about 1100°C was pulverized. Similarly, No. 1 in Table 1. Pb powder shown in each column of 7.8, 9, 11.12 and No. Pb-Sb alloy powders having the chemical compositions shown in columns 1 to 6.10 were obtained by an air atomization method in which molten metal at 500 to 850°C was powdered. Then, the aluminum alloy powder has an average particle size of 30 g.
Pb or Pb-Sb alloy powders were added in the proportions shown in the column of added amount of individually added Pb or Pb alloy powder in Table 1 and mixed in a V-blender, and each mixed powder was made into a columnar shape with a diameter of 170 mm. 2. Otonf/
Cold isostatically formed into a billet at cm2 of hydrostatic pressure,
These billets were extruded at 400°C while being entirely covered with a pure aluminum plate, and No. 1 ~6,8
, 10.11, thickness 2mm, width 110mm, N
o. For 7.9.12, the thickness is 3mm and the width is 110mm.
A plate-shaped extruded product was obtained. The state of each extruded material after extrusion is also shown in Table 1. As is clear from the results shown in Table 1, No. 2.5,
No. to of the present invention alloy, and No. 3. In comparison alloy No. 4, a sound extruded material was obtained even at a thickness of 2 mm. On the other hand, No. 2 has a smaller amount of Sb added in the Pb-Sb alloy powder than the alloy of the present invention. 1 comparative alloy, and Pb-Sb
No. 1 with a larger amount of alloy powder than the alloy of the present invention. In all comparative alloys No. 6, melting of the Pb-Sb alloy occurred. In addition, among the comparative alloys in which Pb single powder was added and mixed,
Extruded material No. 2 mm thick. 8. In 11, ear cracking and melting occurred. When making an extruded material with a thickness of 3 mm, No. 1 with a Pb powder addition amount of 5% by weight. l2, 8% by weight NO. Regarding No. 9, a sound extruded material was obtained, but
16% by weight NO. Pb dissolved out in the extruded material No. 7. Friction and abrasion test Inventive alloy No. 1 obtained a sound extruded material. 2.5,10
and comparative alloy No. Each of the extruded materials in 3.4 and 9.12 was rolled several times, annealed at 350°C for 5 hours, cut out, and surface polished to produce test materials. Friction and wear tests were conducted under the conditions shown. The results are shown in Table 3. Table 2: Friction and wear test conditions Table 3: Friction and wear test results As shown in Table 3, the present invention alloy No. 2. 5
．． Comparative alloy No. 10 is a comparative alloy in which Pb is added as a single powder.
It shows seizure resistance equal to or better than 9.12. On the other hand, No. 2 has a higher amount of S'b in the Pb-Sb alloy powder than the alloy of the present invention. Comparative alloy No. 3, and No. 3 with a smaller amount of Pb-Sb alloy powder than the invention alloy. It can be seen that all comparative alloys No. 4 have inferior seizure resistance than the invention alloy. Inventive alloy No. 1 obtained extruded and rolled materials with good fatigue test results.
2.5, 10 and comparative alloy No. For each of the rolled products in 3.4 and 9.12, roll rolling (reduction rate of 48%) was performed with a steel plate having a thickness of 1.7 mm and a C content of 0.10% by weight, and then rolled at 350°C for 10 hours. After annealing, we added machining to create a prototype bearing. A fatigue test was then conducted on each prototype bearing under the conditions shown in Table 4. The results are shown in Table 5. Table 4: Fatigue test conditions Table 5 Table 2 Fatigue test results The aluminum-based bearing alloy according to the present invention has at least a lubricant component and a hard component among the lubricant component, hard component, reinforcing component, and grain refinement component in text A. Pb-Sb alloy powder containing Sb: 25-50% by weight is added to aluminum alloy powder containing φ at a ratio of 5-20% by weight, and a billet is formed by extrusion molding.
The generation of a liquid phase during extrusion is suppressed, and the effect of Pb, which is added alone in the past, is not lost, so extrudability is extremely good, and it also has excellent fatigue resistance and scorching properties. This is a bearing alloy with excellent properties. As shown in Table 5, alloy No. 1 of the present invention in which Pb-Sb alloy powder was added as the sole additive powder. 2. 5 and 10 are comparative alloy Nos. 5 and 10 in which Pb alloy powder was added as a single powder.
It was confirmed that the fatigue strength was higher than that of 9.12.

【Effect of the invention】

Patent applicant: Nissan Motor Co., Ltd. Patent applicant KonuDC Co., Ltd.

Claims (1)

[Claims] (1) Pb-Sb alloy powder containing Sb: 25 to 50% by weight is added to aluminum alloy powder containing at least a lubricating component, a hard component, a reinforcing component, and a grain refining component in Al. Added at a rate of 5 to 20% by weight.
An aluminum bearing alloy with excellent fatigue resistance and seizure resistance, which is made by extruding a billet formed from mixed powder.